Transformer-less 2 kW non isolated 400 VDC/230 VAC single stage micro inverter

Today's inverters in homes are considered too large for homeowners, although they are typically only the size of a picnic cooler. If they were smaller, one believes that more homes would entertain using them for solar-power, as well as bringing electricity to remote areas of the world where electrical energy is not distributed. The key goal of this project was to reach an inverter power density in excess of 50 W/cubic inch(3W/cm³) in a volume of under 40 cubic inches - a feat which had never been done before using current inverter technology based on 4 IGBT H-bridge. Existing commercial products that meet telecom and industrial requirements achieve 98% peak efficiency with a power density of 17W/cubic inch (1W/cm³). Increase the power density to reach a level close to 150W/cubic inch (10W/cm³) is yet challenging whilst it is not easy to further improve efficiency of such a H-bridge topology. Introducing GaN switches does not suffice to reduce the inverter volume. Thus several H-bridges topologies have been evaluated with the aim to make the inverter output working in ZVS mode at high frequency and reducing inductors size. GaN drivers withstanding dV/dt more were not yet available on the market and a new circuits based on usual dV/dt immunity had to be designed to sustain such conditions. New thermal approaches have been simulated and optimized in order to reduce heatsink sizes whereas MLCC capacitors have been assembled in an innovative design to cool down the overall system. The reduced gate drive and switching losses of GaN Systems' GS66508P GaN power MOSFETs were critical to thermal and power density goals. A specific EMC emission has been applied to the common mode filter in order to have low level noise.